1. Field of the Invention
The present invention relates to a starter for a vehicle.
2. Description of Related Art
Japanese Patent Application Laid-open No. 2009-191843 filed by the applicant of the present application describes a starter which can be advantageously used for an idle stop apparatus. This starter is provided with an electromagnetic switch of the tandem solenoid type including a first solenoid for pushing out a pinion of the starter toward a ring gear of an engine through a shift lever, and a second solenoid for interrupting a current supplied to a motor by opening and closing a main contact, the first and second solenoids being disposed in tandem in the axial direction of the starter. Since the first and second solenoids can be controlled independently from each other, that is, since the timing to push out the pinion and the timing to supply a current to the motor can be controlled independently from each other, this starter can be used advantageously for an idle stop control apparatus.
The idle stop control apparatus is an apparatus which enables automatically stopping an engine of a vehicle by cutting supply of fuel to the engine when the vehicle is stopped at an intersection on a red light, or stopped due to traffic jam, and automatically restarting the engine by causing the starter to operate when a predetermined restart condition is met (for example, when the vehicle driver releases the brake pedal, or shifts the transmission to the drive range) thereafter. Vehicles using such an idle stop control apparatus are increasing in number, because it contributes to reduction of emission of carbon dioxide and fuel consumption.
The starter described in the above patent document has a configuration in which a plunger is attracted by a magnetic force (an attraction force of an electromagnet) generated by the first solenoid to push out the pinion through the shift lever coupled to the plunger, the armature shaft of the motor and the pinion shaft being coupled coaxially with each other through an epicyclic gear device.
There is also known a speed reduction type starter in which the armature shaft of a motor and the pinion shaft are disposed in parallel to each other, and the rotation of the armature shaft is transmitted to the pinion shaft through a reduction gear device. For example, refer to Japanese Patent No. 4207854. The speed reduction type starter as described in this patent document is configured to push out the pinion shaft toward an engine in interlock with a plunger included in an electromagnetic switch which is disposed coaxially with the pinion shaft.
However, the electromagnetic switch of the starter as described in the former patent document has a problem in that its axial length is large, because the first and second solenoids are disposed in tandem in the axial direction of the starter. In the speed reduction type starter as described in the latter patent document, the electromagnetic switch is disposed coaxially with the pinion shaft. Accordingly, if the tandem solenoid type electromagnetic switch described in the former patent document is used in the starter as described in the latter document, the axial length of the starter including the pinion shaft further increases, causing it difficult to be mounted on a vehicle.
In addition, due to the long axial length compared to the conventional speed reduction type starter as described in the latter patent document, since the position of an M-contact bolt (a motor-contact bolt) fixed to a resin cover of the electromagnetic switch is shifted greatly in the axial direction, workability of connection of a motor lead drawn from the motor to the M-contact bolt may become worse.